Att 5 - Preliminary Stormwater Detention

Two locations have been identified to provide the storage tanks required. Tank 1 is
proposed to be located under the 8 scooter bays adjacent to Shop 2 and will discharge to
the stormwater pit near the Elm St and Opal St intersection. Tank 2 is proposed to be
located under car parks 1 and 2 and discharge to the stormwater pit located on Opal St near
the eastern property boundary.

Allowing for 1% fall from the invert of the tanks to the invert of the pit and 400mm for the
top of the detention tank and wearing course, the combined storage capacity of tanks 1 and
2 is in excess of 30kL.

These could be constructed from poured in-situ tanks or by pre-constructed structures such
as Humes Storm Trap (or equivalent product).

It is expected that once a stormwater quantity model is completed as part of the
Operational Works application, the likely required stormwater detention will be between
5m3 and 10m3 (considerably less than the 24m3 as required by the Brisbane City Council
deemed to comply solution).

This correspondence and the accompanying Preliminary Stormwater Management Layout
demonstrates that there is adequate area within the proposed development to
accommodate the required on-site detention.

If you have any queries in relation to the proposed stormwater detention for 34 Elm St,
Cooroy, please do not hesitate to contact Chris Gibberd on 0490 530 793.

Yours sincerely,




Chris Gibberd (RPEQ)
Principal Engineer
360 Civil Consulting Pty Ltd